Clean bench

bench/Bench.hs

@@ -15,7 +15,7 @@ paths =
     ]
 
 solutions :: [(Integer, [Day], FilePath)]
-solutions = filter (\(n, d, p) -> length d > 1) $ zip3 [1 ..] days paths
+solutions = filter (\(n, d, p) -> not (null d)) $ zip3 [1 ..] days paths
 
 makeGroup :: (Show a) => (a, [Day], FilePath) -> Benchmark
 makeGroup (n, d, f) =
@@ -33,5 +33,5 @@ makeBenchmarks f = zipWith name [1 ..] . map (makeBench f)
 groups :: [Benchmark]
 groups = map makeGroup solutions
 
-main =
-    defaultMain groups
+main :: IO ()
+main = defaultMain groups